diff --git a/crates/blockifier_reexecution/src/main.rs b/crates/blockifier_reexecution/src/main.rs
index 0010237f33d..261994643d6 100644
--- a/crates/blockifier_reexecution/src/main.rs
+++ b/crates/blockifier_reexecution/src/main.rs
@@ -5,12 +5,12 @@ use blockifier_reexecution::state_reader::test_state_reader::{
     SerializableOfflineReexecutionData,
 };
 use blockifier_reexecution::state_reader::utils::{
+    guess_chain_id_from_node_url,
     reexecute_and_verify_correctness,
     JSON_RPC_VERSION,
 };
 use clap::{Args, Parser, Subcommand};
 use starknet_api::block::BlockNumber;
-use starknet_api::core::ChainId;
 use starknet_gateway::config::RpcStateReaderConfig;
 
 /// BlockifierReexecution CLI.
@@ -80,14 +80,14 @@ fn main() {
             println!("Running RPC test for block number {block_number} using node url {node_url}.",);
 
             let config = RpcStateReaderConfig {
-                url: node_url,
+                url: node_url.clone(),
                 json_rpc_version: JSON_RPC_VERSION.to_string(),
             };
 
             reexecute_and_verify_correctness(ConsecutiveTestStateReaders::new(
                 BlockNumber(block_number - 1),
                 Some(config),
-                ChainId::Mainnet,
+                guess_chain_id_from_node_url(node_url.as_str()).unwrap(),
                 false,
             ));
 
@@ -101,6 +101,7 @@ fn main() {
                 "./crates/blockifier_reexecution/resources/block_{block_number}/reexecution_data.\
                  json"
             ));
+            let chain_id = guess_chain_id_from_node_url(node_url.as_str()).unwrap();
 
             // TODO(Aner): refactor to reduce code duplication.
             let config = RpcStateReaderConfig {
@@ -111,7 +112,7 @@ fn main() {
             let consecutive_state_readers = ConsecutiveTestStateReaders::new(
                 BlockNumber(block_number - 1),
                 Some(config),
-                ChainId::Mainnet,
+                chain_id.clone(),
                 true,
             );
 
@@ -134,7 +135,7 @@ fn main() {
             SerializableOfflineReexecutionData {
                 serializable_data_prev_block,
                 serializable_data_next_block,
-                chain_id: ChainId::Mainnet,
+                chain_id,
                 old_block_hash,
             }
             .write_to_file(&full_file_path)
diff --git a/crates/blockifier_reexecution/src/state_reader/errors.rs b/crates/blockifier_reexecution/src/state_reader/errors.rs
index 8d15f1de1c0..95ba3ff6d77 100644
--- a/crates/blockifier_reexecution/src/state_reader/errors.rs
+++ b/crates/blockifier_reexecution/src/state_reader/errors.rs
@@ -10,6 +10,8 @@ use thiserror::Error;
 #[derive(Debug, Error)]
 #[allow(clippy::enum_variant_names)]
 pub enum ReexecutionError {
+    #[error("Cannot discern chain ID from URL: {0}")]
+    AmbiguousChainIdFromUrl(String),
     #[error(transparent)]
     Rpc(#[from] RPCStateReaderError),
     #[error(transparent)]
diff --git a/crates/blockifier_reexecution/src/state_reader/utils.rs b/crates/blockifier_reexecution/src/state_reader/utils.rs
index f10ba3afe5a..491f8b2c592 100644
--- a/crates/blockifier_reexecution/src/state_reader/utils.rs
+++ b/crates/blockifier_reexecution/src/state_reader/utils.rs
@@ -19,11 +19,24 @@ use crate::state_reader::errors::ReexecutionError;
 use crate::state_reader::test_state_reader::{
     ConsecutiveStateReaders,
     OfflineConsecutiveStateReaders,
+    ReexecutionResult,
 };
 
 pub const RPC_NODE_URL: &str = "https://free-rpc.nethermind.io/mainnet-juno/";
 pub const JSON_RPC_VERSION: &str = "2.0";
 
+pub fn guess_chain_id_from_node_url(node_url: &str) -> ReexecutionResult<ChainId> {
+    if node_url.contains("mainnet") {
+        Ok(ChainId::Mainnet)
+    } else if node_url.contains("sepolia") && !node_url.contains("integration") {
+        Ok(ChainId::Sepolia)
+    } else if node_url.contains("integration") {
+        Ok(ChainId::IntegrationSepolia)
+    } else {
+        Err(ReexecutionError::AmbiguousChainIdFromUrl(node_url.to_string()))
+    }
+}
+
 /// Returns the fee token addresses of mainnet.
 pub fn get_fee_token_addresses(chain_id: &ChainId) -> FeeTokenAddresses {
     match chain_id {